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Category: Dolphin lover
From: sara_gibrael@hotmail.com
Date: 20 May 2002
Time: 20:31:54
Whales & Dolphins. HOW LONG DO WHALES LIVE ? The limited information available suggests that mortality rates are low and that dolphins & whales are usually long-lived. NAME LIFESPAN (Years)* Harbour Porpoise 15 Bottlenose Dolphin 40 Beluga Whale 25-30 Spotted Dolphin 45 Killer Whale (Male) 50+ Killer Whale (Female) 70+ Short Finned Pilot Whale 60 Sperm Whale 65 Humpback Whale 35 Minke Whale 45 * All these are maximum rather than average life spans. CAN WHALES SMELL ? Dolphins and Whales have largely lost the smell of airborne smell that exists in large mammals. They may have lost this sense when the nostrils disappeared from the front or the beak to the top of the head. The nostril or 'blowhole' is for the most part closed except when the animal breathes at the surface. This exchange of air is very rapid and 'air smelling' must be of limited use. DO WHALES SLEEP ? Whales have to be conscious to breathe. This means that they cannot go into a full deep sleep because they would then suffocate. They have solved this by allowing one half of their brain sleep at a time. This has been determined by doing studies on dolphins. They sleep about eight hours a day and Rapid Eye Movement sleep, usually associated with dreaming has been recorded only very rarely. Some scientists claim they do not have REM sleep at all. HOW DOES A WHALE ADAPT TO THE DIFFERENT PLACES IT GOES TO ? Unlike most other mammals, dolphins and whales do not have thick coats of hair to keep them warm, instead they have a layer of insulating fat called blubber which can be as thick as 50cm in some species. Some whales dive to great depths and in doing so are subjected to enormous pressure. To accomplish this without getting the 'bends', the whale has developed a number of ways to protect itself from being injured. The whale is a breath-hold diver, taking down only the air contained in its lungs and respiratory passages so there is little nitrogen to dissolve in the blood and tissues which would give it the bends. HOW LONG CAN A WHALE STAY UNDERWATER ? The Bottlenose Whales and Sperm Whales can stay underwater for up to two hours on long dives. Most of the large whales, like the Blue and Fin rarely stay down for longer than 40 minutes while dolphins such as the Bottlenose usually stay down for less than five minutes. The Common Dolphin dives for less than three minutes. HOW BIG IS A BLUE WHALES’ HEART ? A female's heart of this particular species weighed 1540lbs back in 1947. For an average Blue Whale a dog can run along some of its blood vessels, it weighs as much as 6,000 small children and you could park a car in its mouth. WHAT IS THE HABITAT OF THE BLUE WHALE ? Most Blue Whales live in the Southern Hemisphere while smaller populations inhabit the North Atlantic and North Pacific. They migrate long distances between low latitude winter mating grounds and high latitude summer feeding grounds and are often seen in parts of California, Sea of Cortex, Canada and the Northern Indian Ocean. -------------------------------------------------------------------------------- The Worlds' Oceans are being used as dustbins for toxic chemicals, heavy metals, untreated sewage and all our other waste products. -------------------------------------------------------------------------------- Hundreds of thousands of plastic items are dumped into the worlds' oceans every day. They pose a serious threat to dolphins and whales, which may swallow plastic bags or get tangled up in the rubbish and die slowly of starvation or strangulation. -------------------------------------------------------------------------------- Chilean Fishermen call dolphins and porpoises the 'silly ones' because they are so friendly and easy to kill. They harpoon and shoot the animals to use them for crab fishing. Fish is the official crab bait but dolphin meat is much cheaper so they use that instead. -------------------------------------------------------------------------------- Dusky Dolphins are the prime target hunts of Peru where as many as 20,000 dolphins and porpoises are killed deliberately or accidentally each year. Hunting these animals is illegal but the law is rarely enforced. -------------------------------------------------------------------------------- Identifying dolphins at sea is a challenge. Many species look alike although no two dolphins are exactly the same. Apart from scarring and other markings they have gained over the years their natural coloration often differs from one individual to the next. -------------------------------------------------------------------------------- Some dolphins can hurl themselves as high as 15 feet into the air and then turn somersaults before re-entering the water. -------------------------------------------------------------------------------- Whale and dolphin watching is one of the fastest growing tourist activities in the world. Some dolphins live in remote areas far out to sea but in many parts of the world with a little luck, they can be seen quite close inland. A close encounter with a dolphin is a thrilling and memorable experience. -------------------------------------------------------------------------------- Some experts believe that dolphins may be telepathic and therefore could be able to communicate without the need for speech or visual signals. -------------------------------------------------------------------------------- The bottlenose dolphin shows a more striking range in size between individuals than any other dolphin species. Physically mature adults vary in length from just under 2m to nearly 4m and in weight from 330lbs to 1430lbs. -------------------------------------------------------------------------------- Monkey Mia on the remote Western Coast of Australia has become one of the country's leading tourist attractions. Wild bottlenose dolphins have been greeting people there for more than 30 years although there is now concern about the level of dependency shown by the dolphins on their human "friends". -------------------------------------------------------------------------------- Swimming in the frothy wake of a boat of ship seems to be a favourite pastime of many dolphins, they surf in the waves, twist and turn and swim upside down in the bubbles. -------------------------------------------------------------------------------- Dolphins appear to devote much of their time to play although it is unclear how much of this is for pure pleasure and how much has a greater purpose. Dolphins frequently play with pieces of seaweed, pebbles and other objects in the sea - carrying them around in their mouths or pushing them with their flippers. -------------------------------------------------------------------------------- The permanent 'smile' of the bottlenose dolphin and many other members of this family, is an expression that cannot be changed. Dolphins continue to smile when they are feeling aggressive, when they are intense pain and ever after death. -------------------------------------------------------------------------------- Risso's dolphins are frequently covered in white scratches and scars, which are usually caused by the teeth of other Risso’s dolphins, and this gives them a distinctly "battered" appearance. -------------------------------------------------------------------------------- Every year hundreds or even thousands of dolphins are found stranded, alive and dead, on beaches all over the world. Some of these strandings are easy to explain but others remain a mystery.
